220 21647 article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Introducing the returntype keyword Date: Tue, 13 Oct 2015 17:23:42 +0800 Lines: 95 Approved: news@gmane.org Message-ID: References: <24e315aa-2daf-4e47-933b-1f45157a0f79@isocpp.org> <0884ab8b-672b-459a-9143-f522ea7ebf1d@isocpp.org> <3374ec49-e50e-40dc-8936-46e642a93ebf@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_5C936C5C-D7C5-4ADA-9ECB-7DD61A07ED9B" X-Trace: ger.gmane.org 1444728260 7748 80.91.229.3 (13 Oct 2015 09:24:20 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 13 Oct 2015 09:24:20 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBMU36OYAKGQETTXYDHQ@isocpp.org Tue Oct 13 11:24:15 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qg0-f70.google.com ([209.85.192.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Zlvoc-00077d-JB for gclcip-std-proposals@m.gmane.org; Tue, 13 Oct 2015 11:24:14 +0200 Original-Received: by qgez77 with SMTP id z77sf13133098qge.2 for ; Tue, 13 Oct 2015 02:24:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:content-type:message-id:mime-version :subject:date:references:to:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=JG8Pc6RTvcrDhh255NlXkX6usaiilW4KSvlx9RtSbPw=; b=g8x2c0UBgHs6O8/IsJG5ASuu2ZTqTmKwCZ3vuiDR4EGy3ICBuQT1QPkEyh2BeJjO15 2I05bQ39QLWSy2RbAlwOhCm7lb0ptXPp1F5kcQShvoF1078oZ4WK1NW13Ni5M7b50jnC Kego4g0edvzsYJXTRGl9SLM4CURx0MijA4dSrt0cUXde/eJ+9IEX8q/BjhGsFHlRmu6Z riZXUKIyBhGOzQFUwyBne97bB9cWBn8hVZ1ooXvGRzxwOF18Bju6JXTnGL7cxD3k687y qsfD3o08gHANKzslsY0ES2ox4F/kW5x+pYB1lvrrJiw1ZnvQvRiKN8q1cxR/+gnyhLQr CXsQ== X-Gm-Message-State: ALoCoQnQ7Cy7A4oNNwFLna3AFJQJpIj13NNVuqCXx0bYbnU39emzWDFY18rHC75YMwhN3f33tjFa X-Received: by 10.129.103.4 with SMTP id b4mr27893603ywc.24.1444728244019; Tue, 13 Oct 2015 02:24:04 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.137.140 with SMTP id t12ls1665879ioi.34.gmail; Tue, 13 Oct 2015 02:24:02 -0700 (PDT) X-Received: by 10.107.129.218 with SMTP id l87mr7824518ioi.181.1444728242850; Tue, 13 Oct 2015 02:24:02 -0700 (PDT) Original-Received: from mail-pa0-x22d.google.com (mail-pa0-x22d.google.com. [2607:f8b0:400e:c03::22d]) by mx.google.com with ESMTPS id m194si2051557iom.139.2015.10.13.02.24.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Oct 2015 02:24:02 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::22d as permitted sender) client-ip=2607:f8b0:400e:c03::22d; Original-Received: by pacex6 with SMTP id ex6so16137792pac.3 for ; Tue, 13 Oct 2015 02:24:02 -0700 (PDT) X-Received: by 10.66.100.165 with SMTP id ez5mr39004084pab.63.1444728242373; Tue, 13 Oct 2015 02:24:02 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.44.92]) by smtp.gmail.com with ESMTPSA id d13sm2684679pbu.20.2015.10.13.02.23.47 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 13 Oct 2015 02:24:01 -0700 (PDT) In-Reply-To: <3374ec49-e50e-40dc-8936-46e642a93ebf@isocpp.org> X-Mailer: Apple Mail (2.2104) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::22d as permitted sender) smtp.mailfrom=potswa@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:21647 Archived-At: --Apple-Mail=_5C936C5C-D7C5-4ADA-9ECB-7DD61A07ED9B Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 2015=E2=80=9310=E2=80=9313, at 5:08 PM, Klemens Morgenstern wrote: >=20 > decltype(return) some_value; > return &some_value; What=E2=80=99s the problem? There=E2=80=99s already a diagnosable rule for = mismatched return expressions in a deduced function. > Now this is obviously utter nonsense, but a situation were the return typ= e actually depends on the decltype(return) is rather likely with this sort = of programming. The error is easier to avoid, not easier to commit, if the deduced return t= ype is available to the programmer. --=20 ---=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. --Apple-Mail=_5C936C5C-D7C5-4ADA-9ECB-7DD61A07ED9B Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On 2015=E2=80=9310= =E2=80=9313, at 5:08 PM, Klemens Morgenstern <klemens.morgenstern@gmx.net> wrote:<= /div>
decltype(return) some_value;
return &some_value;

What=E2=80=99s the problem? There=E2=80=99s already a diagnosable= rule for mismatched return expressions in a deduced function.

Now this is obviously utter nons= ense, but a situation were the return type actually depends on the decltype= (return) is rather likely with this sort of programming.

The error = is easier to avoid, not easier to commit, if the deduced = return type is available to the programmer.

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